The objective of this study is to enhance treatment effectiveness for obesity by investigating interventions for improving exercise adherence in obese females. Regular exercise is one of the strongest predictors of success in weight management, and increased physical fitness is associated with a variety of positive psychophysiological benefits. However, the obese are generally characterized by low activity levels and poor adherence to exercise recommendations. The proposed experimental study will evaluate the effectiveness of three interventions designed to improve exercise adherence as follows: Group A: Cognitive-behavioral groups for 4 months, followed by 4 months of maintenance groups. Group B: Cognitive-behavioral groups for 4 months, without maintenance. Group C: Attention control intervention. Follow-up assessments will occur at 4, 8, 14, and 20 months. All subjects will receive the same exercise and nutrition information for four months. They will also have equal access to a fitness facility for the entire study period. The primary hypothesis is that the maintenance program will improve longterm exercise adherence as assessed by estimated cardiorespiratory fitness, attendance at exercise classes, and self-reported exercise. To explore psychosocial factors associated with the adoption and maintenance of exercise, measures of exercise self-efficacy, body image, eating disorder symptoms, and social support will be included. Relapse analysis will be used to describe factors associated with exercise cessation.